1. Field of the Invention
The present invention relates to an apparatus for reading information code, and in particular, to the apparatus that has the capability of reading information codes, such as two-dimensional codes and bar codes, from an object to be read, such as an LCD (Liquid Crystal Display) on the surface of which is covered by a transparent protective layer.
2. Description of the Related Art
There has been known a handy information code reading apparatus capable of optically reading information codes, such as bar codes and two-dimensional codes. Such an apparatus has been disclosed by, for example, Japanese Patent Laid-open (KOKAI) publication Nos. 2001-307012 and HEI1(1989)-196680.
This type of information-code reading apparatus is shown in FIG. 9, in which, by way of example, the fundamental configuration of a handy two-dimensional code reading apparatus is schematically provided. The apparatus has a case 1, which can be operated manually by a user. At the tip of the case 1 is formed a rectangular reading opening 1a. In addition, inside the case 1 are a plurality of LEDs (light emitting diodes) 2 serving as light sources, light receiving means including a reflection mirror 3, an imaging lens 4, and a light receiving element 5 such as a CCD area sensor, and a processing circuit 6. The processing circuit 6 is responsible for various types of processing including decoding signals from the light receiving element 5.
This apparatus is handled to locate the reading opening 1a closer to an object 7 to be read (i.e., a label or others) on which a two-dimensional code (such as a QR code) is recorded, with the attitude of the opening 1a being almost parallel to the object. Then, the reading operation is carried out such that light is radiated onto the object 7 to be read from the LED 2 through the reading opening 1a, so that its reflected light can be received through the reading opening 1a. The received light is sent to the light receiving element 5 with the help of the reflection mirror 3 and the imaging lens 4 to read two-dimensional codes. During this reading operation, the case 1 is handled so that a reading light axis O passing through the various components of the light receiving means is set to be nearly perpendicular to the surface of the object 7 to be read.
By the way, it has been general that the conventional information code reading apparatus of this type is produced to read information codes printed on pieces of paper (normally, labels) serving as the object 7 to be read. On the other hand, a new system has recently been conceived which is capable of reading information codes displayed on the screen of, for example, a mobile phone or a liquid crystal display (LCD) unit 8 incorporated in a PDA (Personal Digital Assistance) or others, as shown in FIG. 10.
However, the LCD unit 8 has the screen of which surface is covered by a transparent protective layer 9 (for example, made of a plastic or glass material). Hence, in cases where information codes are to be read from the screen of the LCD unit 8, the illumination light from the LEDs 2 is specularly reflected on the protective layer 9, and the reflected light is projected onto the light receiving element 5. This makes it difficult to read information codes by the light receiving element 5. In addition, as shown in FIG. 10, if the light source (LEDs 2) is disposed within an angle of field “A” of the imaging lens 4, the light source itself shadows in the light reflected from the protective layer 9 to the light imaging element 5, which makes an accurate reading difficult.